A railway vehicle generally includes several motors of this type, positioned on the bogies and driving the wheels. To do this, the electric motors transform into a rotary movement an electric power produced by the generator of the vehicle or directly provided from a power supply cable.
These motors generally consist of a rotary portion, the rotor, and of a fixed portion the stator, attached in a frame, which plays a protection and insulation role and receives a circuit for cooling the motor.
The frame is a metal casing, generally in an iron alloy for maximum strength, for example in cast iron or in steel. Several methods for manufacturing such a motor frame are known.
A first method consists of molding the frame in a single part, generally in cast iron, which has advantages notably in terms of cost. Further, a frame in a single part is more rigid and solid. However, the thereby obtained structure is heavy and bulky.
In order to reduce the mass of the frame, the use of a structure in several parts welded to each other is known, notably comprising two end plates connected through parallel bars. In order to compensate for the lower resistance of such a structure, steel is generally used for its making, which substantially increases the manufacturing cost of the frame. Further, a frame consisting of several welded parts is more likely to undergo distortions under the effect of internal constraints generated by the cooling of the welding areas. These distortions may be passed onto the stator, which may be detrimental to proper operation of the electric motor by forming hot points or a magnetic unbalance.
An object of the invention is to provide a motor stator frame which is more resistant to distortions and less expensive, while retaining reduced bulkiness.